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H3 2008 Alpha Adventure Transfer Case / 4wd bind

Dyno Dan

Active Member
Messages
35
Location
Southwest Montana
Wife has noticed binding at full lock. I was able to replicate and the. I would switch to 4H lock, then 4 L lock, and then back to 4H. After a few circles and reverse it feels bind free. Wait a few hours or drive the next day and the bind is back.

After a bunch of searching it seems that the TC shift fork can be the culprit. It also appears that early 2008’s could very well have the plastic fork like early models that was prone to wear / fail.

Since I’m the new owner, I have no idea on history and there weren’t any records provided. It certainly looks like the trans or TC have been removed before since I see zip ties and other tattletales of repair”. All the being said, is there a way to ID my TC? I understand that RPO codes would indicate, transfer case Nr4 or Nr6, but my glovebox sticker is illegible. Is there a way to physically ID? Like I mentioned I have the Adventure package since there is a 4L lock button. I would cringe to find out if the 4:1 TC was replaced with a service replacement 2.6:1 version......but I’m not too concerned about that right now.

I figure I’ll start with making sure there’s adequate fluid in the TC. Any guidance, comments, or technical details are very welcome.
 

4speedfunk

Well-Known Member
Messages
4,212
Location
Tardville
Drain the fluid and check it for metal particulates. This is the easiest way to see if something is up inside the t-case. It’s normal to see dark fluid but shiny metal dust is bad. There is a magnet inside the t-case but you can’t get to it unless you tear it down (great job GM). It doesn’t do much anyway because most of the parts that wear are either aluminum or magnesium...both non-ferrous. But the magnet will capture small steel particulate.

The 08-up t-cases have a small snubber plate inside them that was added to help control chain slap, and keep a loose chain from wearing through the case. This small aluminum plate is held In place by two grossly undersized screws. These screws can come out and this allows the snubber to flop around and get ground up into dust by the rotating internals. The magnet will capture the steel screws but not the aluminum snubber plate. This can cause the intermittent binding issue, (But so can a worn shift fork or chain).

Your AP t-case should be the 4:1 low range, unless someone swapped it out. Very easy to tell as the low range is well...VERY low. AP models will snap your neck when they shift into second gear at 5mph. They feel like a tractor in low range.

It could also be a bad cv joint on the half shafts. This is very common and also creates binding. If your TC shifts through all modes and you don’t get any dash lights, it’s probably not the shift fork or encoder. They almost always get stuck in one mode when either part goes bad.
 
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Dyno Dan

Active Member
Messages
35
Location
Southwest Montana
Wonderful info, thank you. I’ll drop the fluid and see what that looks like to start with. All the mode selections seem to be respected by the TC, so that’s good. Also yes, in 4L the 1>2 shift surprised the hell outta me .... haha.

Any other tattletales that CV joints are bad? Like I mentioned, the bind is inconsistent and diagnosing is challenging at best.
 

Dyno Dan

Active Member
Messages
35
Location
Southwest Montana
Changed the TC fluid, it was a deep / dirty dark reddish brown (didn’t take a pic sorry). I replaced with Deleon VI. While I was under there I also changed the front differential fluid with Mobil 1 75w90. I can see where there has been some oil leaking on each side of the engine towards the back (by starter and by oil filter). I sprayed some degreaser on the block, TC, and transmission. After it soaked a while I ran my pressure washer as best I could underneath and cleaned up some gunk.

So, it didn’t bind when I was done with the job. I let it sit for 1.5 hours and then loaded up the family to head to the lake. It was binding again. Switch to 4H locked and it felt the same. Went to 4L locked and then back to 4H.....still felt locked. Backed up, spun some circles and I could not free it up / unlock. By the time I got to the end of my driveway (.25 miles) it was free. We drove 45 minutes to and from the lake and no drama. I’m still confused though :)
 

650Hawk

Well-Known Member
Messages
480
Location
SoCal
...I have the Adventure package since there is a 4L lock button.

ALL H3's have a 4L lock button, even non-Adventure. If you have the Adventure package (on your 2008 Alpha) it will have, from left to right, 4H - 4H Lock - 4L Lock then you will have the rear Locker button and finally the TC button. That Locker button is the key; no locker, no Adventure pkg.
 

Dyno Dan

Active Member
Messages
35
Location
Southwest Montana
ALL H3's have a 4L lock button, even non-Adventure. If you have the Adventure package (on your 2008 Alpha) it will have, from left to right, 4H - 4H Lock - 4L Lock then you will have the rear Locker button and finally the TC button. That Locker button is the key; no locker, no Adventure pkg.

Yes, I have those buttons in that order. My fault for not giving a better explanation.

As an update everything seems to be functioning fine at this point I’ve put on 40 or 50 miles on 3 different drive cycles. Each one had no hint of bind, the full lock turning is smooth.
 

alrock

El Diablo
Staff member
Messages
10,442
Location
Scottsdale
It is possible for the buttons to stick, causing the vehicle to stay in 4H lock (or other modes). It's also possible that you have a worn shift fork, but it finally managed to shift.
 

Dyno Dan

Active Member
Messages
35
Location
Southwest Montana
It’s still happening intermittently. At this point I think I would chalk it up to the shift fork. Almost seems like it just slides / shifts on its own, which from what I understand is consistent with a warn shift fork.
 

Dyno Dan

Active Member
Messages
35
Location
Southwest Montana
Uggh. It’s consistently intermittent :)

Drive out in the morning and it’s normal, then go a few miles down the road and pull into a parking lot and it’s very apparent. Sometimes you can free it up by going to 4H locked or 4L locked and then back to 4H.

I suppose it’s best to park it and have a look inside the TC. Anything else to consider or check before I go down that road?
 

Jeepwalker

Well-Known Member
Messages
857
Location
WI
There is a magnet inside the t-case but you can’t get to it unless you tear it down (great job GM).

Lot of xfer cases are like that. Jeep NPs that were installed in millions of Jeeps ..come to mind.
 

Dyno Dan

Active Member
Messages
35
Location
Southwest Montana
I got a wild hair today and decided to remove the transfer case and have a closer look.

What a pain. I was doing great, but that TC would not come out unless you remove a couple studs AND remove the trans cross member. I must have wrestled with it for 1.5 hours before I submitted and removed the transmission crossmember with my son. The studs would hit the trans adapter no matter which way we rotated, pushed, cursed.

In the end it’s out, time for beer

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Dyno Dan

Active Member
Messages
35
Location
Southwest Montana
Any tips or tricks?’ Any gotchas or pitfalls to look out for? I read something about the need to remove some of the gears, and of course the need to get them reinstalled in the correct position or “timed”? Any other “should do stuff” while I’m in there?
 

Dyno Dan

Active Member
Messages
35
Location
Southwest Montana
Done deal. Function tested and it’s working great through all modes. Drove into town last night, so I had some time on pavement / and did some tight turns. It was nice and smooth and also along the way it never magically engaged. Feels good!
 
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